The present invention relates to a sifter-screening machine for bulk or loose material, especially flour, including inlet means for the material, downstream thereof a screen through which the material can be conveyed via an air stream, and downstream thereof an outlet means for screened material.
With one known sifter-screening machine of this type, the material that is to be screened is drawn into the machine via an inlet that is embodied as a suction connection. The material passes into a sieve drum in which beaters rotate at high speed and throw the material and the air against the sieve drum. The air, with the loosened flour particles, passes the screen and is drawn off via the separator. The material is separated off in the separator and passes, after passing through the sieve drum, into an annular region that is delimited radially inwardly by the sieve drum and radially outwardly by the housing wall. The material passes out of this annular region into the separator, which tapers toward the bottom in a funnel-shaped manner. This funnel-shaped narrowing has the drawback that during discharge the loose material is increasingly compressed in conformity with the increasing cross-sectional narrowing of the outlet, and is hence compacted. This readily leads to blockage and to breakdown of the material stream, because as a result of the cross-sectional narrowing and the compaction of the loose material in the outlet, a bridge formation occurs that prevents a continuous discharge of the loose material.
It is an object of the present invention to embody a sifter-screening machine of the aforementioned general type in such a way that the loose material can be uniformly conveyed through the sifter-screening machine without the danger of breakdown of the material stream.